We describe the nest and nest site, and provide the first description of the eggs and nesting behavior of the Black-bellied Wren (Thryothorus fasciatoventris) in central Panama. Nine nests were found near tree-fall gaps, swamps, and roads in moist tropical forests. Nests were dome-shaped with a circular side entrance. They were composed chiefly of strips of dead palm fronds, and were generally built in places where leaf litter and other debris had accumulated at the convergence of several vines near the forest floor. Both males and females participated in building the nest. Clutch size was three, and eggs were laid on consecutive days. Egg color varied from creamy to beige with faint to dark brown speckles that were more concentrated at the blunt end. Females were the sole incubators, but males fed the incubating females. Only the female brooded the nestlings once they hatched, but both parents fed the nestlings.